聚焦型之方向性表面電漿激發

Abstract

在此篇論文中，我們提出一種嶄新的方法去達到可控性表面電漿激發。在同軸聚焦型Kretchmann架構下，將空間非勻質入射光場以高數值孔徑物鏡聚焦於金屬薄膜表面以激發金屬表面電漿，藉由設計入光瞳處空間非勻質極化光中輻射型偏極化與角偏極化分部達到近場表面電漿波的傳播方向與激發面積的操控。 利用調變遠場入射光極化分部來調變近場表面電漿的方法，不僅可以省去許多金屬表面奈米結構的設計，更能夠藉由特殊設計的入射極化光分部，在金屬表面產生各種干涉圖案，甚至能夠同時在金屬表面激發出多道獨立傳播的表面電漿波，這是過去以往文獻中所未被提出的。此方法相信對於許多表面電漿相關領域都能夠有很大的幫助。

A novel method is proposed in which surface plasmon polaritons (SPPs) can be manipulated as a controllable SPPs’ source from far field. The capability of beam steering and shaping can be achieved by using collinear Kretchmann configuration in conjunction with spatially inhomogeneous polarized beam which consists of radial and azimuthal polarization in specific section of pupil plane. Without the need of additional nano-sized aperture, protrusion or near-field features, we are able to modify the SPPs excitation condition via various local electric field components mediated by the far-field pupil engineering. Various interfering phenomena are observed by different plasmonic excitation formations. Furthermore, we are able to simultaneously excite multiple SP waves which has never been demonstrated before. Proposed method will certainly has a potential impact on carrying out various SPPs excitations for plasmonic devices in next generation.